Introduction

This issue of the University of Dayton Review presents papers in the area of philosophical hermeneutics. This was the theme of the Eleventh Annual Philosophy Colloquium of the Department of Philosophy of the University of Dayton, held in March 1982. All of the papers included in this issue were presented at the colloquium

The correlates of work in a post-AFDC world: the results from a longitudinal state-level analysis

Much of the research that has followed welfare reform and new policies such as the Temporary Assistance for Needy Families (TANF) has focused on identifying the variations in how different states have put the new policy into practice. Less is known however, about how this new policy affects the ability of recipients to earn a living through work. We use panel data from the state of Illinois and examine what explains labor force participation and performance among current and recent TANF recipients. We use both cross-sectional and longitudinal methods to analyze our data. Our results indicate that human capital factors such as education, job skills, and health are important determinants of labor market participation and performance. In addition, we find that long term welfare recipients are equally likely to participate and perform well in the labor market as shorter term welfare recipients. Finally, government housing subsidy appeared to have a positive effect on labor force participation and performance

Plio-Pleistocene submarine glaciogenic morphology of the Chukchi Shelf, Arctic Ocean

Ongoing research aims to constrain the extent of grounded ice shelves around the Arctic Ocean during the last glacial periods. Here, the Chukchi region is of special interest because of its broad, shallow shelf. In general, little is known about possible sources and the areal extent of ice sheets if any existed on the Chukchi shelf. Bathymetric and sub bottom profiler data from the Chukchi Sea margins as well as from the Arlis Plateau to the west show complex patterns of glaciogenic erosion like Mega Scale Glacial Lineations (MSGL) at water depths of more than 500 m. The different directions of those MSGL indicate the presence of ice shelves and streams and point to an East Siberian Ice Sheet of unknown size. On the Chukchi Shelf, no evidences for the existence of an ice shelf for water depths shallower than 350 m have been described yet. We re-processed 2D multi-channel seismic data acquired in 2011 from R/V Marcus G. Langseth to investigate glaciogenic features on the shallow shelf. These data reveal new insights into the formation of the northern Chukchi Shelf. The first up to 500 ms TWT of the seismic data show strongly eroded reflectors and reworked sediments. Additionally, small-scale channels with a few tens of meters width and a depth of 20 ms TWT disrupt the horizons below the reworked layers. Furthermore, the seismic data show channels with widths up to few km and depths up to 150 ms TWT as well as truncated well stratified reflectors. All above described features can be observed on parts of the Chukchi shelf with water depths shallower than 900 m

The eastern Rio Grande Rise: a magmatic province

The Rio Grande Rise and Walvis Ridge were formed during the opening of the South Atlantic. Both structures were emplaced in the Late Cretaceous when the Tristan-Gough plume was located on or close to the Mid-Atlantic spreading ridge. In the last decade, several wide-angle seismic experiments unraveled the crustal structure of the Walvis Ridge, showing that it is composed of thickened oceanic crust. In contrast, it is debated if the RGR is entirely of volcanic origin or if it also contains fragments of continental crust. In 2019, Wide-angle refractions and gravity data were acquired along two NNE-SSW trending transects crossing the western and eastern RGR to study the nature of the crust and the evolution of the RGR. We will present first results from the new transect crossing the eastern RGR (profile AWI-20190100) and compare it with the crustal structure of the transect crossing the western Rio Grande Rise (profile AWI-20190200). P-wave velocity models derived by forward modelling, supplemented by a gravity models, constrain its crustal and upper mantle structure along both profiles. Our results show that the crust of the eastern RGR is thinner and only half as thick (15 km) in comparison to the western RGR. The crustal velocities along both lines are very similar. Evidences from the seismic velocities for the existence of a continental fragment are missing along both transects. While a high-velocity upper mantle is partly present below the western RGR, such high upper mantle velocities are not observed along the eastern profile. In summary, the seismic velocity structure of the RGR and the conjugate Walvis Ridge are very similar

Distribution of oceanic crust in the Enderby Basin offshore East Antarctica

Seismic reflection and refraction data were collected in 2007 and 2012 to reveal the crustal fabric on a single long composite profile offshore Prydz Bay, East Antarctica. A P-wave velocity model provides insights on the crustal fabric, and a gravity-constrained density model is used to describe the crustal and mantle structure. The models show that a 230-km- wide continent–ocean transition separates stretched continental from oceanic crust along our profile. While the oceanic crust close to the continent–ocean boundary is just 3.5–5 km thick, its thickness increases northwards towards the Southern Kerguelen Plateau to 12 km. This change is accompanied by thickening of a lower crustal layer with high P-wave velocities of up to 7.5 km s–1, marking intrusive rocks emplaced beneath the mid-ocean ridge under increasing influence of the Kerguelen plume. Joint interpretations of our crustal model, seismic reflection data and magnetic data sets constrain the age and extent of oceanic crust in the research area. Oceanic crust is shown to continue to around 160 km farther south than has been interpreted in previous data, with profound implications for plate kinematic models of the region. Finally, by combining our findings with a regional magnetic data compilation and regional seismic reflection data we propose a larger extent of oceanic crust in the Enderby Basin than previously known